As a logician/philosopher it is difficult to find out how revered B Russell is in the math community. As a philosopher in my opinion he's the best. And on the philosophical encyclopedia, plato.standford.com he is the 4th most cited philosopher, but it's difficult to find out how seriously mathematicians take him. In Peter Smith's Godel without Tears, he calls the Principia to be frankly quite sloppily written and several of the axioms are highly dubious. In Russell's autobiography, My Philosophical Development (1959), Russell himself writes that he only knew of 6 people that had the 3rd volume of the PM, implying that most people give up after the first volume. So if we were to make a list of the top 20 mathematicians, then where would Russell fit into that hierarchy in your opinion.